1. Field of the Invention
This invention relates to apparatus for testing the volumetric output of fuel injector system components and more specifically to apparatus of this type which provides rapid, accurate and continuous data.
2. Prior Art
Prior art techniques for testing the output of fuel injectors for diesel engines and the like have been time consuming and not as accurate as is desirable. Generally, in such test equipment, fluid pumped by the cam driven injector is collected in a measuring device and read at the end of a predetermined number of injector strokes. In one such tester, the fluid is collected in a graduate and the volume of fluid collected at the end of the preset number of stokes is read visually from the scale. In such a tester, fluid is generally accumulated for 1000 strokes in order to obtain a reading with an accuracy of .+-. 1%. At the end of the test cycle, the graduate must be emptied to prepare it for the next test or to repeat the test. Clearly, this method of testing injector output takes considerable time.
Another type of prior art fuel injector tester is disclosed in British Pat. No. 1,185,897. In this tester, fuel from the injector is accumulated in a cylinder where it displaces a spring-biased piston. A pointer connected to the piston rod through a rack and pinion arrangement is deflected relative to a scale which indicates the volume of fluid in the cylinder. Flow to the cylinder is terminated after a preset number of strokes so that the position of the pointer at that time is an indication of the volume of fluid metered by the injector in the preset number of strokes. When a button is pressed to initiate a new test, a valve is opened to divert the fluid to a reservoir as the spring returns the piston to the starting position. With this apparatus 100 strokes of the injector are used in the test cycle which speeds up the testing, but the accuracy remains about the same as in the graduated tube method. As in the case of the graduated tube tester, the presentation of the results of the test are no longer available when a new test cycle is initiated. In addition, this apparatus is subject to errors resulting from operation of the start and stop solenoids during the measuring period. Errors can also be induced in this equipment and in the graduated tube apparatus by fluid which is retained in the cylinder or graduated tube between measurements. There is also difficulty in these prior art systems of maintaining calibration.
It is a primary object of this invention to provide an improved fuel injector tester which provides an accurate measurement of fuel injector output with a minimum number of injector strokes.
It is also an object of the invention to provide such a tester which is reset in minimum time.
It is a further object of the invention to provide such a tester which rapidly and continuously repeats the tests.
It is another object of the invention to provide such a tester which offers a continuous presentation of the test results while repeated tests are being made.
It is still another object of the invention to provide such a tester which offers a digital display of the test results.